Discussion of Background and Prior Art
Substantial advances have been made in robotics in recent years and the use of multiple manipulator arms integrated into a single robotic device is not new, as shown in U.K. patent No. 2,014,879. Such a robotic device enables a single robotic system consisting of multiple manipulator arms, perhaps each arm having different dexterity and payload requirement, to perform complex tasks.
In robotic devices like the one described in Colechia, et al., U.S. Pat. No. 3,451,224, which discloses a two-armed robot for use in connection with submarines and underwater research, the two manipulator arms are each attached to larger, main positioning arms. This arrangement allows the two manipulator arms to share the actuators and linkages on the main arm. In practice this arrangement would use the main arm joints to deploy the manipulator arms to a position where they could work. The main arm joints, however, would not be suitable for fine positioning or simultaneous coordinated use of the manipulator joints.
Tasks requiring cooperative use of two or more manipulator arms can be accomplished if the arms can be properly coordinated. But in close quarters, and depending on the configuration, there may be insufficient room for one arm to maneuver without interfering with the other. Introducing mechanical stops to prevent collision would seriously limit the range of motion of each arms. Coordinating multiple arms with computer controlled systems that incorporate collision-avoidance algorithms may prohibit interference but is computationally expensive. Another approach to inhibit arm collisions is to place mechanical stops on the arm joints but this may adversely affect the ranges of motion of the arms.
Although there are robotic devices with independent multiple arms, and devices which have cooperating manipulator arms attached to a main positioning arm, the inventor is not aware of any prior art relating to robots which have multiple forearms depending from a common elbow configuration.
The term "forearm" implies a subset of a more complex robotic arm and in particular, the series of joints and linkages comprising the elbow joint and the end effector, which for simplification refers to both the "wrist" and "hand" of the robotic arm. For example, a "forearm" would not be suitable for use as a stand-alone manipulator but is intended for use in conjunction with a main arm linkage and shoulder joint(s). The elbow refers to the first joint past the end effector.